JMRTD provides both a card side application
(the "passport applet") and a host side
API for accessing ePassports.
The passport applet makes it possible to create your own passports
(in case you're starting your
own country). The applet is written in
Java Card.

The host side Java API can be used in different scenarios:

Inspection system:
The API makes it possible to read, decode, and validate
the information on the chip
(for some of these tasks JMRTD will need access to the issuing country's
country signing root certificates).

Enrollment / personalization system:
The API also allows to encode information by complying to the relevant standards.

Testing framework:
JMRTD was developed initially
to test conformance and security of ePassport implementations.